光子学报, 2010, 39 (6): 961, 网络出版: 2010-08-31
基于级联相移线性啁啾光纤光栅的梳状滤波器设计
Design of Optical Comb Filters Based on Cascaded Phase-Shifted Linearly Chirped Fiber Gratings
级联相移线性啁啾光纤光栅 传输矩阵法 F-P谐振腔理论 梳状滤波器 Cascaded phase-shifted linearly chirped fiber grat Transfer matrix method Fabry-Perot resonant cavity theory Comb filter
摘要
为了获得反射带宽大、信道间隔均匀的高性能梳状滤波器,提出一种基于级联相移线性啁啾光纤光栅的新型梳状滤波器的结构设计.利用传输矩阵法和法布里-珀罗谐振腔理论,数值分析了该梳状滤波器中啁啾光栅的级联方式、啁啾量、折射率调制量和级联处的相移量对光栅反射谱特性的影响.结果表明:对应不同的级联方式,反射峰存在疏密变化,即两个级联光栅的啁啾量同号时,反射峰分布均匀对称,可设计均匀滤波器;而两个啁啾量异号时,反射峰呈现出疏密渐变的特性,可设计非均匀滤波器.此外,光栅啁啾量增加,反射谱带宽增大,但是反射率降低,而增大折射率调制量,可以提高反射率;级联处的相移量改变时,每个反射峰位置发生移动,从而可以通过改变相移量选择滤波窗口.
Abstract
A novel optical comb filter is designed with two cascaded phase-shifted linearly chirped fiber gratings.According to the transmission matrix method and Fabry-Perot resonant cavity theory,the characteristics of reflection spectrum of the optical comb filter are numerically analyzed for the different combinations of two chirp gratings,the value of chirp,the index modulation and the phase-shift.The results show that the distribute density of reflection peaks is different for the different combinations of two chirp gratings,that is,the spacing between reflection peaks is equal if the signs of two chirps same,it can be used to design a uniform filter; on the other hand,the distribute of reflection peaks shows the characteristic density gradient if the signs of two chirps opposite,which can be used to design a non-uniform filter.And the greater the chirp of gratings,the wider the bandwidth of reflection spectrum of the filter,and the lower the reflectivity; however, the reflectivity will be improved with the increase of index modulation; furthermore each of the reflection peaks moves with the change of phase-shift,which is useful to select a filter window by changing the phase-shift.
周骏, 苑红伟, 徐铁峰, 张玲芬, 马伟涛. 基于级联相移线性啁啾光纤光栅的梳状滤波器设计[J]. 光子学报, 2010, 39(6): 961. ZHOU Jun, YUAN Hong-wei, XU Tie-feng, ZHANG Ling-fen, MA Wei-tao. Design of Optical Comb Filters Based on Cascaded Phase-Shifted Linearly Chirped Fiber Gratings[J]. ACTA PHOTONICA SINICA, 2010, 39(6): 961.